This invention relates generally to percutaneous electrical therapy systems for medical use. In particular, the invention relates to a percutaneous electrical therapy system providing axial support to an electrode during insertion of the electrode into a patient""s tissue.
Electrical therapy has long been used in medicine to treat pain and other conditions. For example, transcutaneous electrical nerve stimulation (TENS) systems deliver electrical energy through electrode patches placed on the surface of a patient""s skin to treat pain in tissue beneath and around the location of the patches. The efficacy of TENS systems in alleviating pain is questionable at best, however.
More recently, a technique in which electrodes are placed through the patient""s skin into the target tissue has been proposed. Percutaneous Neuromodulation Therapy (xe2x80x9cPNTxe2x80x9d) (also sometimes called Percutaneous Electrical Nerve Stimulation or xe2x80x9cPENSxe2x80x9d) using percutaneously placed electrodes achieves significantly better pain relief results than TENS treatments using skin surface electrodes. This therapy is described in Ghoname et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation for Low Back Pain,xe2x80x9d JAMA 281:818-23 (1999); Ghoname et al., xe2x80x9cThe Effect of Stimulus Frequency on the Analgesic Response to Percutaneous Electrical Nerve Stimulation in Patients with Chronic Low Back Pain,xe2x80x9d Anesth. Analg. 88:841-6 (1999); Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation (PENS): A Complementary Therapy for the Management of Pain Secondary to Bony Metastasis,xe2x80x9d Clinical Journal of Pain 14:320-3 (1998); and Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation: An Alternative to Antiviral Drugs for Herpes Zoster,xe2x80x9d Anesth. Analg. 87:911-4 (1998). The contents of these references are incorporated herein by reference.
Thus far, PNT practitioners have used percutaneously placed acupuncture needles attached to waveform generators via cables and alligator clips to deliver the therapy to the patient. This arrangement and design of electrodes and generator is far from optimal. For example, the prior art has not addressed the need to provide axial support to a percutaneous electrode during insertion of the electrode into a patient""s tissue prior to electrical therapy. It is therefore an object of this invention to provide a electrode insertion axial supporter for use with an electrical therapy system.
It is a further object of this invention to provide a percutaneous electrical therapy system having electrodes and electrode assemblies that are safe, efficacious, inexpensive and easy to use.
Other objects of the invention will be apparent from the description of the preferred embodiments.
The invention is a percutaneous electrical therapy system providing electrode axial stability during electrode insertion. In a preferred embodiment, the system includes a control unit; an electrode electrically connectable to the control unit to deliver electrical therapy to a patient, the electrode having a sharp point at a distal end adapted to be inserted into a patient""s tissue; and an electrode insertion axial supporter adapted to provide axial support to the electrode during insertion of the electrode into the patient""s tissue. In one embodiment, the electrode insertion axial supporter includes an electrode inserter, such as a guide element at one end of the inserter, the guide element being adapted to provide axial support to the electrode during insertion of the electrode into the patient""s tissue. The guide element could be, e.g., an aperture in the electrode inserter or a channel in the electrode inserter.
The system may also include a mechanical connection between the electrode inserter and a proximal end of the electrode. In some embodiments, the mechanical connection is adapted to remain connected after the sharp point of the electrode has been inserted into the patient""s tissue. In other embodiments, the mechanical connection is adapted to release the electrode after insertion of the sharp point of the electrode into the patient""s tissue. The mechanical connection may be an actuator adapted to be movable with respect to the guide element.
In some embodiments, the system also includes an electrode insertion pain reducer adapted to reduce pain experienced by the patient during insertion of the sharp point of the electrode into the patient""s tissue. In other embodiments, the system may also include an electrode angle of entry controller adapted to control the electrode""s entry angle during insertion of the sharp point of the electrode into the patient""s tissue.
The invention also includes the percutaneous electrode and electrode insertion axial supporter described above apart from the control unit.
The invention is described in further detail below with reference to the drawings.